The present invention relates to apparatus for heating and/or cooling a material, such as foodstuffs and the like, and, more particularly, to novel radiant-energy cooking and/or heating apparatus having a honeycomb coverplate.
It is well known to provide foodstuff-cooking apparatus having a heating means positioned to provide infrared energy at a cooking surface. One prior-art heating and/or cooking appliance utilizes an unprotected infrared source, such as a heating element and the like, and a reflecting surface to direct the infrared energy from the heating source to a foodstuff load, such as a cooking utensil and the like, which rests on a metallic grid placed across the mouth of the reflector. In another prior-art heating and/or cooking appliance, the metallic grid is replaced by a surface member which is transparent to infrared radiation. This surface member is typically a coverplate formed of a high-temperature, high-strength material, such as quartz or a glass which has been chemically strengthened.
The cooking/heating apparatus advantageously utilizes a layer of visible-wavelength radiation-absorbing material, as described and claimed in co-pending application Ser. No. 478,826, filed on even date herewith, assigned to the assignee of the present invention and incorporated herein by reference. By absorption of at least a portion of the visible-wavelength radiation emitted by a heating means operating at a relatively high temperature, the user does not suffer from visual discomfort during the use of radiant-energy apparatus having an increased amount of foodstuff-cooking infrared-wavelength radiation emitted therefrom.
In all radiant-energy cooking systems hitherto known to us, the coverplate must not only transmit significant amounts of infrared-wavelength energy, but must also be of great strength, as the coverplate is normally at a relatively high temperature during cooking unit operation and must be able to withstand severe thermal shock in the event that cold liquids are spilled upon the hot coverplate. Special materials are often required, which increases the coverplate cost. The coverplate thickness must often be such that additional absorption of infrared-wavelength radiation occurs, thereby raising the coverplate temperature and requiring even greater strength and thermal-shock resistance. It is highly desirable to provide a coverplate for radiant-energy apparatus, which coverplate is fabricated of relatively low cost material and yet has relatively high mechanical strength, thermal-shock resistance and infrared-wavelength energy transmissivity.